It has long been desirable to ventilate noxious fumes from toilet enclosures (witness the half-moon cutout in outhouse doors). It has become even more desirable since the advent of indoor plumbing, as evidenced by U.S. Pat. No. 136,105 (Smith; 1873) which discloses an exhaust flue connected at an upward angle to the bottom of a toilet bowl, before the trap.
Typically, the problem is resolved by providing a ventilation fan that exhausts air from the toilet enclosure, but it is not always convenient or even possible to vent the exhausted air to the outside of a building. A less common alternative is to cause the fumes to be passed into the sewage outlet of a toilet beyond a fume trap (typically a water filled drain trap). According to typical building codes and common practice the sewage outlet leads directly to a sewer stack that is vented to the outside.
A relatively simple way to implement this kind of ventilation is by using a retrofittable device such as is disclosed in U.S. Pat. No. 5,570,477 (Rodriguez; 1996) wherein a portable ventilator draws air from the toilet bowl and exhausts it via a tube that extends through the water trap and into the sewer pipe.
Additional work is required (e.g., replacing the floor flange) in order to install a retrofit device as disclosed in U.S. Pat. No. 5,351,344 (Phillips; 1994) wherein an evacuation system can be retrofitted on a standard water closet (see FIGS. 1, 2, 4). A wet/dry vacuum bypass motor pulls air (or overflow fluid) from under the toilet seat and exhausts into a modified closet ring (37) (floor flange) having a down-angled exhaust outlet (42). A pressure switch mounts under the toilet seat for automatic operation limited by a timer. A manual override switch is also provided. The system plugs into an AC power wall outlet. U.S. Pat. No. 6,295,656 (Tillen; 2001) discloses a retrofittable system with an upper insert (24) mountable between the tank and top of the bowl, and a lower insert (30) mountable between the bowl and the floor for communicating with the sewer pipe opening. A fan (26) between the inserts draws gases in through the bowl water spray openings under the rim. A backflow valve flap (82) is used to prevent backflow. The fan can be operated by water, a hand-cranked spring drive, or a battery-operated electric motor. Manual activation of the fan is by means of a push button switch (98, see FIG. 13) that is incorporated into the tank flush handle, and the fan is deactivated by flushing.
Other ventilation systems are less visible due to being built into a toilet, thereby requiring replacement of the toilet with a new toilet having a built-in ventilation system. U.S. Pat. No. 4,800,596 (Menge; 1989) discloses a built-in system drawing gas from the bowl through passages into the water storage tank, through a liquid seal, a vacuum blower, and out into the sewer pipe. The blower is operated by a float switch in the tank. A major concern of this patent appears to be the liquid seal for preventing backflow of sewer gases. U.S. Pat. No. 4,103,370 (Arnold; 1978) discloses a toilet with a built-in system including an intake manifold interposed between the seat and top periphery of the bowl. A suction blower is mounted inside the tank and blows air out through a one way, rubber flap-type check valve (107, FIGS. 10-14) and a deflector (104c) into the discharge duct (105) after the trap, and leading to the sewer pipe. It is automated with a pressure switch under the seat and an optional pressure pad on the floor. A timer continues running the blower for a predetermined time after a user leaves. U.S. Pat. No. 6,073,275 (Klopocinski; 2000) discloses a built-in system that draws gases from the bowl, through a fan (64), an odor extraction trap and valve assembly (66), and vents through a downward angled nozzle (53) into the sewer pipe flange shared by the toilet outlet (50). It uses the trap 66 instead of an outlet valve to prevent backflow. U.S. Pat. No. 3,805,304 (Ikehata; 1974) discloses a built-in system providing a separate exhaust channel (7) under the bowl lip, a fan blade (15) in a chamber (11) built-in to the toilet, the fan being driven by an external motor (13), and an exit passage (16) from the chamber into the sewer drain. There does not appear to be any separate backflow prevention devices. The fan is controlled by a floor mounted pressure switch (17).
It is an object of the present invention to provide a high quality, premium toilet with a toilet ventilation system that automatically operates to remove odors from the toilet bowl area in a direct and efficient manner. It is an object to make the ventilation system mostly built in so that it is relatively unobtrusive in appearance. It is an object to removably attach the active parts unobtrusively on the exterior of the toilet for simplified installation, maintenance, and replacement as needed. It is an object to automatically prevent backflow of sewer gases and/or sewage through the toilet ventilation system. It is an object to enable normal toilet use when the active parts are not attached to the toilet.